Divide your students into small groups, explaining that each group will be responsible for researching and presenting its findings on one particular segment of the 40-week gestation period it takes for a human fetus to fully develop.

2.

To determine the number of weeks for each segment, divide the 40 weeks of gestation by the number of groups your class has formed. Give the segments consecutive numbers (Segment 1, Segment 2, and so on), and assign each group one segment.

3.

Ask each group to use the research materials you have provided plus source materials from the library and the Internet to research the changes that both mother and fetus undergo during the gestation period the group has been assigned. (For example, students will find that by the end of the 12th week of gestation, the fetus has developed all of its organs and major body structures. They will find that during the final three months of pregnancy, a woman's growing uterus takes up a huge space; her spine curves with the extra weight; her abdominal organs and lungs are pushed out of place; and her heart works harder and grows larger.)

4.

When each group's research is complete, have students create a verbal description and a visual presentation showing the group's findings and detailing the changes that occur in both fetus and mother during the group's gestation period. Encourage students to include sonogram images if they are available.

5.

When students' work is complete, compile the presentations into an illustrated time line of fetal development, and have each group present its findings to the class.

Men produce approximately 500 million sperm per ejaculation, but women produce only one ovum per month. Speculate about the evolutionary reasons that this uneven balance developed.

2.

Describe the various tests that doctors can use to examine a fetus while it is still inside its mother's womb. What can these tests determine? What risks are associated with performing them?

3.

Cloning is the process by which a new individual is "created" from the genetic material of a single person, rather than getting half of its genetic material from one parent and half from the other. This creates an exact genetic copy of the gene donor. Though scientists do not think that cloning will be possible for humans for a very long time, some day it may become a reproductive option. Should cloning be viewed as just another tool that can allow infertile couples to have children? Under what circumstances might human cloning be acceptable?

4.

Tests have shown that by mid-pregnancy a fetus has developed all five senses. By the time a baby is born its brain has developed enough to process some of the information it receives through those five senses. Despite these facts, however, adult humans find it impossible to remember their first few months alive outside the womb, let alone the nine months they spent inside it. Speculate about the reasons for this huge memory gap.

5.

A mother delivers nutrients and oxygen to the fetus through the umbilical cord. The umbilical cord may also deliver such substances as medication, toxins, drugs, and alcohol, however. Debate whether expectant mothers should be subject to laws that protect the health of the fetus. Should pregnant women be barred from holding potentially dangerous jobs?

6.

Human babies are born completely helpless. They must be fed and cared for by their parents for years before they could possibly survive on their own. Many other animals are born helpless, but remain so for a much shorter period of time. Still others can live nearly independently from the moment they are born. Speculate about the reasons behind these differences. What evolutionary advantages and disadvantages does a longer childhood offer the human species?

Reproductive Technology Debate
Recent advancements in modern medical technology have enabled many infertile couples to conceive and bear children. One side effect of some of these medical advancements, however, is multiple births, or two or more children born at a time, when the couple wanted only one baby. The world recently witnessed the birth of two sets of surviving sextuplets, for example, as well as one set of octuplets in which one of the eight babies died. Because a human woman is not anatomically equipped to carry so many fetuses at once, several dangerous complications can accompany these pregnancies: the children may face a lifetime of medical and learning difficulties, the medical care for the mother and the babies can cost millions of dollars, and the financial and emotional costs of raising so many children can devastate some families. Still, there's no denying the benefits—countless couples that could never have had children in the past are now able to do so. Divide your class into three groups for a debate on the present and future use of these reproductive technologies. One group should argue for the unlimited use of reproductive technologies, another for the complete abolishment of such technologies, and the third for a limited use of such technologies (a limit that the group can define on its own). Each group should prepare by researching the science, history, and future of reproductive technology. At the end of the debate, poll the class to see where most students stand on this issue. Did anyone's opinion change in the course of this activity?

Haywire Hormones
Hormones are vitally important for the processes of sexual maturation, menstruation, fertilization, fetal implantation, pregnancy, and birth. Divide your students into groups that will each study the role of one of the following hormones in one of the just-mentioned processes: testosterone, estrogen, progesterone, gonadotropin-releasing hormone (GnRH), follicle stimulating hormone (FSH), luteinizing hormone (LH), human chorionic gonadotropin (HCG), oxytocin/prostaglandins, and prolactin (PRL). Where in the body is the hormone produced? At what stage in human development does the hormone appear? What other hormones or bodily events influence the production of the hormone? What bodily event (or events) does the hormone stimulate? What organ or group of organs does the hormone affect? What happens if the hormone is absent or overabundant? Can the hormone be regulated with pharmaceuticals? To present its material to the class, each group should create an illustrated handout that outlines the information it has gathered. You can conclude the activity with a discussion about the delicate balance of hormones in the human body. What advantages or disadvantages does such a complex chemical system offer the human race?

Beginning Life: The Marvelous Journey from Conception to Birth
Geraldine Lux Flanagan. DK Publishing, 1996.
The story of the remarkable journey that all of us make from conception to birth, this graphic book unravels the mysteries of that inner world in which we are first formed as human beings. Complete with a stunning sequence of photographic images and clear and sensitive description, this is a truly compelling narrative, one that will sharpen your understanding and expand your sense of wonder.

Life Before Birth: Normal Fetal Development
Marjorie A. England. Year Book Medical Publishing Co., 1996.
This unique, profusely illustrated guide to the development of the normal fetus from conception to birth uses literally hundreds of color illustrations to graphically depict each stage of fetal development. It also incorporates imaging illustrations, including CT and MRI scans, to depict what modern science has revealed about the complex process of fetal development.

Definition: The shortening and thickening of a functioning muscle or muscle fiber.Context: With a heat-sensitive camera, you can see the waves of hot muscle action sweeping across a woman's stomach during a contraction.

Definition: One of the typically paired essential female reproductive organs that produce eggs and female sex hormones.Context: On each side of the top of the uterus, a fallopian tube reaches out toward an ovary.

Definition: A technique involving the formation of a two-dimensional image used for the examination and measurement of internal body structures and the detection of bodily abnormalities.Context: Many babies will be first glimpsed with ultrasound.

This lesson plan may be used to address the academic standards listed below. These standards are drawn from Content Knowledge: A Compendium of Standards and Benchmarks for K-12 Education: 2nd Edition and have been provided courtesy of theMid-continent Research for Education and Learningin Aurora, Colorado.

Grade level: 6-8, 9-12Subject area: scienceStandard:
Understands the genetic basis for the transfer of biological characteristics from one generation to the next.Benchmarks: Benchmark 6-8:
Knows that reproduction is a characteristic of all living things and is essential to the continuation of a species.

Benchmark 9-12:
Knows features of human genetics (e.g., most of the cells in a human contain two copies of each of 22 chromosomes; in addition, one pair of chromosomes determines sex [XX or XY]; transmission of genetic information to offspring occurs through egg and sperm cells that contain only one representative from each chromosome pair; dominant and recessive traits explain how variations that are hidden in one generation can be expressed in the next).

Benchmark 9-12:
Knows sound health practices in the prenatal period that are important to the health of the fetus and young child (e.g., diet, refraining from cigarette smoking or use of alcohol or other drugs).

Benchmark 9-12:
Understands a variety of physical, mental, emotional, and social changes that occur throughout life and how these changes differ among individuals (e.g., young adulthood, pregnancy, middle age, old age).